JPH041162B2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to a casing coupling device, and in particular,
The present invention relates to a casing coupling device suitable for coupling steam turbine casings.

[Technical background and problems]

FIG. 1 is a sectional view showing a general steam turbine.

In this steam turbine, an inner casing 3 is housed inside an outer casing 1, and a rotor 7 having turbine blades 5 is provided within the inner casing 3. Further, a steam supply port 9 is formed in the outer casing 1, and an expandable communication pipe 11 is fitted into the steam supply port 9. Furthermore, this communication pipe 11 is connected to an annular nozzle box in the inner casing 3. 13.

Furthermore, a nozzle diaphragm 17 with a nozzle 15 is provided on the inner wall of the inner casing 3 . Further, gland packing heads 19 are attached to both ends of the external casing 1, and the rotor 5
This prevents steam leakage caused by the rotation of the

In such a steam turbine, high-temperature, high-pressure steam flows from the steam supply port 9 through the communication pipe 11 into the nozzle box 13. The steam is guided as a high-speed flow from the nozzle of the nozzle box 13 to the turbine blade 5, and imparts kinetic energy to the rotor 7 via the turbine blade 5. The steam then passes through nozzle 1 of each nozzle diaphragm 17.
5, it becomes a high-speed flow again and is sequentially guided to the next stage of blades 5.

Each time the steam passes successively through the turbine blades 5 and nozzles 15, it performs work and expands, reaching the high-pressure turbine outlet section 21. There, 1/1 of the steam supply port 9
The steam pressure will be about 4 to 1/8. Thereafter, the steam is led out of the outer casing 1, is reheated through the reheater of the boiler, becomes high-temperature steam again, and is led to the medium and low pressure turbine.

By the way, the outer and inner casings 1,
3 is divided into upper and lower halves on a horizontal plane, and each divided casing is fastened with both tightening bolts 23 and nuts 25, as shown in FIG.
be integrated. As a result, it becomes easy to assemble and separate the outer and inner casings 1 and 3 and to carry the rotor 7 in and out. Further, the flange portion 27, which serves as a joint surface between the upper and lower divided casings, is formed thick.
Thereby, the strength of the flange portion 27 is ensured, and it becomes possible to strongly connect the upper and lower casings by the tightening bolts 23 and the nuts 25, and it is possible to maintain airtightness against internal pressure in the external and internal casings 1 and 3.

The forces acting on both tightening bolts 23 and nuts 25 include not only the internal pressure of the steam, but also the axial tensile force of the bolts 23 generated when the upper and lower casings are strongly connected, and the force due to thermal deformation. This acting force is a very large force.

When this acting force is supported by both tightening bolts 23 and nuts 25, both tightening bolts 23
Since both the nut 25 and the nut 25 are made of a forged material having high yield strength, their fastening strength is large and there is no problem.

However, as shown in FIG. 3, due to the structure of the casings 1 and 3, it is not possible to use both tightening bolts 23, and there is a problem when a stud bolt is used as the presser bolt 29.

In the conventional example shown in FIG.
A through hole 30 is bored in the flange portion 27A of A,
Further, a hole 31 having the same diameter as the through hole 30 is formed in the upper half of the flange portion 27B of the lower casing 1B, facing the through hole 30. Flange part 2
At the bottom of the hole 31 in 7B, there is a presser bolt 29.
A threaded portion 33 that can be screwed into the hole 31 is formed coaxially with the hole 31 . The holding bolt 29 is attached to the flange 27A.
It is inserted into the through hole 30 and the hole 31 from above and is screwed into the threaded portion 33, thereby joining both the flange portions 27A and 27B.

However, the presser bolt 29 is a forged product (mainly Cr
-Mo-V steel, 12Cr-Mo-V steel), and the threaded part 33 is a cast product (Cr-Mo steel, Cr-Mo-V steel).
Therefore, the strength of the threaded portion 33 is equal to that of the presser bolt 29.
Therefore, this threaded portion 33
However, a problem arises in that the force acting on the retainer bolt 29 causes it to break.

To prevent damage to the threaded portion 33, it is generally adopted to oversize the threaded portion 33.
However, in this case, the diameters of the through holes 29 and holes 31 also become large, resulting in a problem that the strength of the flange portions 27A, 27B is reduced.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a casing joining device that can improve the workability and reliability of joining a pair of split casings.

[Summary of the invention]

In order to achieve the above object, a casing joining device according to the present invention includes a through-hole formed in the flange portion of a pair of split casings, and a through-hole formed on the joint surface side of both split casings. forming a large-diameter counterbore portion, further inserting both tightening bolts into the through hole, and providing the both tightening bolts with a bulging portion having a larger diameter than the through hole and a smaller diameter than the counterbore portion, and Nuts having substantially the same strength as the bolts can be screwed onto both ends of the two tightening bolts, and one of the nuts is provided so as to be fixed to one of the split casings via a pin. Therefore, the bulging portions of the two tightening bolts are engaged with the counterbore portions of one of the split casings, and a nut is screwed onto one end of the two tightening bolts protruding outside of the one split casing. Fix the nut to one of the split casings using a pin to prevent rotation. Thereafter, the other split casing is brought into contact with the one split casing, and at the same time, the other ends of the tightening bolts are inserted into the through holes of the other split casing, and the nuts are inserted from the outside of the other split casing. It screws together different nuts.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 is a cross-sectional view showing one embodiment of the casing coupling device according to the present invention, and the same parts as those in the conventional example are given the same reference numerals and the explanation thereof will be omitted.

The flange portion 41 of the upper casing 1A and the flange portion 43 of the lower casing 1B in the outer casing 1 can be joined by abutting their respective joint surfaces 45 and 47. Through holes 49 and 51 are bored in these flange parts 41 and 43,
Both tightening bolts 53 can be inserted into the through holes 49 and 51.

At the axial center position of both tightening bolts 53,
A bulging portion 55 is integrally provided around the periphery. This bulging portion 55 extends outward in the radial direction of both tightening bolts 53.
The bolt 53 is provided in an annular shape along the entire outer peripheral side surface thereof. Furthermore, the outer diameter of this bulging portion 55 is larger than the inner diameter of the through holes 49, 51, and smaller than the inner diameter of counterbore portions 61, 63, which will be described later.

The axial length of both tightening bolts 53 is such that the distance from the center position of both tightening bolts 53 in the bulging portion 55 to the upper end is the thickness of the flange portion 41 and the length of the nut 57 screwed into the upper end of both tightening bolts 53. It is considered to be greater than or equal to the sum of the height of Similarly, the distance from the central position of the bulging portion 55 to the lower ends of both tightening bolts 53 is set to be greater than or equal to the sum of the thickness of the flange portion 43 and the height of the nut 59 screwed into the lower ends of both tightening bolts 53. . Here, the nuts 57 and 59 are made of forged material together with both tightening bolts 53, and therefore both have substantially the same strength.

Furthermore, after the nut 59 is screwed together a certain distance V from the lower end of both tightening bolts 53, the threaded portion of the protruding lower end of both tightening bolts 53 is crushed and fixed by caulking, making it impossible to rotate. bolt 5
Slow fall from 3 is prevented. Here, the constant distance V is the distance between the nut 5 and the upper threaded part of both tightening bolts 53.
All of the effective screw portions of No. 7 are screwed together, and the bulging portion 55
is set to a distance that does not abut against a counterbore portion 61, which will be described later.

The flange portions 41 and 43 of the upper and lower casings 1A and 1B are provided with counterbore portions 61 and 63 coaxially and of the same shape as the through holes 49 and 51, respectively.

The counterbore portion 61 is provided on the joint surface 45 side of the through hole 49 in the flange portion 41, and the counterbore portion 63
are formed on the joint surface 47 side of the flange portion 43 to have a larger diameter than the through holes 49 and 51, respectively. The depth of these counterbore parts 61 and 63 is slightly larger than the axial length of both tightening bolts 53 in the bulging part 55, and at least when the flange parts 41 and 43 are connected by both tightening bolts 53 and nuts 57 and 59. , the bulging portion 55 is set so as not to come into contact with both bottom surfaces of the counterbore portions 61 and 63.

Next, the action will be explained.

First, the double tightening bolts 53 are inserted into the through holes 51 of the lower casing 43, and the bulging portions 55 and counterbore portions 63 are engaged with each other, so that the double tightening bolts 53 are inserted into the lower casing 43 as shown in FIG. hook it on. Next, the nuts 59 are screwed into the lower portions of both tightening bolts 53. Then, when the distance from the lower ends of both tightening bolts 53 to the lower surface of nut 59 reaches a certain distance V, the lower end threaded portions of these tightening bolts 53 are caulked.

Then, replace the upper casing 1A with the lower casing 1B.
The upper parts of both tightening bolts are inserted into the through holes 49 at the same time that the joint surfaces 45 and 47 are brought into contact with each other. In this state, as shown in FIG. 5, the bulging portion 55 is enclosed in the space surrounded by both counterbore portions 61 and 63.

Next, nuts 57 are screwed onto the upper portions of both tightening bolts 53, and are strongly tightened with a tool to connect both upper and lower casings 1A and 1B.

According to the above embodiment, the upper and lower casings 1A,
1B is connected by threading the threaded parts of both tightening bolts 53 and nuts 57, 59 having approximately the same strength, and screwing into mounting holes formed in the upper and lower casings 1A, 1B. Since there are no screws, there is no damage to the threaded portion, and the reliability of the connection between the upper and lower casings can be improved.

Since this threaded portion is not damaged, there is no need to periodically inspect the threaded hole, and maintenance can be facilitated.

In addition, since the bulging portion 55 is engaged with the counterbore portion 63 and the two tightening bolts 53 do not fall off from the lower casing 1B, the workability of joining the casings can be improved. Furthermore, since the nut 59 is fixed by caulking, there is no need to hold the nut 59 with a tool when tightening the nut 57, which further improves workability.

In the above embodiment, the nut 59 is fixed to both bolts by caulking, but instead of this fixation by caulking, the following modification may be used. That is, a pin hole is drilled in the axial direction from the bottom surface to the top surface of the nut 59, and after this nut 59 is screwed and attached to both tightening bolts 53, the flange is synchronously drilled with the pin hole using a drill. A pin hole may be provided in the portion 43, a pin may be inserted into both of these holes, and the lower end of the pin may be caulked.

In this case, in addition to the effects of the embodiment described above, since the nut 59 can be reliably rotated, the workability of tightening the nut 57 can be further improved.

In addition, in the above embodiments and modified examples, the bulging portion 5
Although the upper and lower portions of both tightening bolts 53 have the same diameter with 5 as the boundary, they may have different diameters.

In addition, in the above embodiment and both modified examples,
Counterbore portions 6 on both upper and lower casings 1A and 1B
1 and 63 are provided, however, one counterbore may be provided only in one of the casings. In this case, the flange portions 41, 4
The processing of step 3 can be facilitated.

In the above embodiment, the nuts 57 and 59 are made of the same forged material as the tightening bolts 53, but they may be made of different materials as long as they have approximately the same strength.

〔Effect of the invention〕

As described above, according to the casing joining device according to the present invention, a through hole is formed in the flange portions of a pair of split casings, and the through hole is larger than the through hole on the joint surface side of both split casings. A counterbore portion having a diameter is formed, and a double tightening bolt is inserted into the through hole, and a bulge portion is provided on the double tightening bolt with a larger diameter than the through hole and a smaller diameter than the counterbore portion, and the above-mentioned A nut having almost the same strength as the bolt can be screwed onto both ends of both tightening bolts, and one of the nuts can be fixed to one of the split casings via a pin, so that the split casing can be connected. This has the effect of improving workability and reliability of the connection.

In addition, since the split casing is connected by bolts and nuts that have approximately the same strength on both sides, damage to one of the threaded parts can be effectively prevented, and there is therefore no need to regularly inspect the threaded part. , maintenance can be facilitated.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a typical steam turbine;
Figure 2 is a cross-sectional view showing a conventional casing coupling device that connects both upper and lower casings with tightening bolts, and Figure 3 shows a conventional casing coupling device that connects both upper and lower casings with presser bolts. 4 is a sectional view showing an embodiment of the casing coupling device according to the present invention, and FIG. 5 is a sectional view showing the state before casings are coupled in the same embodiment. 1A...Upper casing, 1B...Lower casing, 45, 47...Joint surface, 49, 51...Through hole, 53...Both tightening bolts, 55...Bulging portion, 5
9...Natsuto, 61, 63...Spot-bore part.

Claims (1)

[Claims] 1. A through hole is formed in the flange portions of the pair of split casings, and a counterbore portion having a larger diameter than the through hole is formed on the joint surface side of both split casings of the through hole, and , a double tightening bolt is inserted into the through hole, a bulge portion is provided on the double tightening bolt with a diameter larger than the through hole and a smaller diameter than the counterbore portion, and the both ends of the double tightening bolt are provided with a bulge portion approximately equal to the bolt. 1. A casing coupling device, characterized in that nuts having the same strength can be screwed together, and one of the nuts is provided so as to be fixable to one of the split casings via a pin. 2. The casing coupling device according to claim 1, wherein the bulging portion is integrally provided along the entire outer peripheral side surface of both the tightening bolts.